1. Field of the Invention
This invention relates to novel (cyclo)alkylenediammonium salts of tetrahalophthalate half-esters and to bisimides prepared therefrom.
2. Description of the Prior Art
As taught in U.S. Pat. No. 3,873,567 (Cyba), British patent 1,287,934 (Raychem), and Sydney M. Spatz and Herman Stone, "Some N-Substituted Tetrabromophthalimide Fire-Retardant Additives," INDUSTRIAL AND ENGINEERING CHEMISTRY PRODUCT RESEARCH AND DEVELOPMENT, Volume 8, pp. 397-398 (1969), N,N'-alkylenebis-tetrahalophthalimides having utility as flame retardants can be prepared by reacting a tetrahalophthalic anhydride with a diaminoalkane in an organic solvent medium. These processes, which produce the bisimides via an amic acid intermediate corresponding to the formula: ##STR2## are difficult to control, present filtration problems, and are less economical than is desirable.